1. Field of the Invention
The invention relates to a method for operating an electrical installation having a plurality of electrical loads which are connected to a basic supply voltage and, in the event of a failure of the basic supply voltage, are connected to a backup voltage, in order to safeguard the supply to the electrical loads for a duration of a backup phase, the backup voltage being provided by means of an uninterruptible power supply unit.
The invention also relates to an electrically driven installation for performing the method.
2. Description of the Related Art
Within installations having an uninterruptible power supply unit it has until now been customary for the uninterruptible power supply unit to shut down its power output after a preconfigured time.
However, the following problems result: the installation, the installation component or the user cannot prepare for the shutdown. Moreover, important interdependencies of the users are not taken into account.
Even an uninterruptible power supply unit that implements a particular shutdown management plan using specific functional modules cannot fully resolve complex dependencies among the users. Inconsistencies and data losses occur when preparing for the impending shutdown. Furthermore, even when the voltage is restored in backup operation the installation cannot continue to be operated problem-free, and thus downtimes occur.
An uninterruptible power supply for a web press is known from EP 1 223 656 A1, in which in the event of a disruption to the supply voltage a control sequence can be triggered, according to which the web press can be brought to a standard defined production halt. In the case of the electrical installation according to EP 1 223 656 A1 there is only one electrical load, namely the web press, which is directly connected to the uninterruptible power supply.
In an electrical installation with a plurality of electrical loads, which can readily be arranged on a decentralized basis in an industrial process, it is disadvantageous that the individual electrical load cannot prepare itself for the impending shutdown in the event of the basic supply voltage failing. As a result, there is a risk of data losses, undefined installation states and damage to workpieces and the installation, because a process or subprocess in progress is abruptly interrupted because of an uncoordinated shutdown.